HKDSE · Answers & Marking Scheme

2022 HKDSE Geography Answers & Marking Scheme

Thinka 2022 DSE-Style Mock — Geography

98 marks225 mins2022
An original Thinka practice paper modelled on the structure and difficulty of that year's HKDSE paper. Not affiliated with or reproduced from the HKEAA.

Section A

Answer all 20 multiple-choice questions. No marks deducted for wrong answers.
20 Question · 20 marks
Question 1 · MC
1 marks
Which of the following conditions favor the development of a wave-cut platform?
(1) Active hydraulic action and abrasion
(2) Steep coastal profile
(3) Continuous rapid deposition of sediments
(4) Waves approaching parallel to the coastline
  1. A.(1) and (2) only
  2. B.(1) and (3) only
  3. C.(2) and (4) only
  4. D.(3) and (4) only

Answer

A

Worked solution

Statement (1) is correct as hydraulic action and abrasion are the primary marine processes that erode the cliff base to form a wave-cut notch. Statement (2) is correct because a steep coastal profile allows deep water near the shore, preventing waves from breaking early and ensuring high wave energy directly attacks the cliff face. Statement (3) is incorrect because rapid sediment deposition would cover the rocky platform, protecting it from further wave erosion. Statement (4) is incorrect because although wave refraction shapes coasts, parallel wave approach is not a necessary condition for platform development.

Marking scheme

Award 1 mark for the correct answer A. No marks are given for incorrect answers.
Question 2 · MC
1 marks
Which of the following are the major obstacles to implementing "redevelopment" compared to "rehabilitation" in old urban areas of Hong Kong?
(1) Fragmented property ownership
(2) High financial compensation costs
(3) Complete loss of local social networks
(4) Inability to improve the local road network
  1. A.(1) and (2) only
  2. B.(1) and (3) only
  3. C.(2) and (4) only
  4. D.(3) and (4) only

Answer

A

Worked solution

Statements (1) and (2) are correct. Acquiring fragmented property titles from numerous individual owners in old buildings is a highly time-consuming obstacle, and the statutory financial compensation (such as Home Purchase Allowance) represents a massive financial burden for developers or the Urban Renewal Authority. Statement (3) is a social consequence/impact of redevelopment, not an obstacle to implementing it. Statement (4) is incorrect because redevelopment allows for comprehensive replanning of land use, which actually facilitates road widening and improvement, whereas rehabilitation (which only repairs existing structures) does not allow for road improvement.

Marking scheme

Award 1 mark for the correct answer A. No marks are given for incorrect answers.
Question 3 · MC
1 marks
The biomass, soil, and litter are the three major nutrient pools in a terrestrial ecosystem. If large-scale commercial logging is carried out in an undisturbed tropical rainforest, how will the biomass pool and soil pool change?
  1. A.Biomass pool increases, soil pool decreases
  2. B.Biomass pool decreases, soil pool decreases
  3. C.Litter pool increases, soil pool increases
  4. D.Litter pool decreases, soil pool increases

Answer

B

Worked solution

Commercial logging directly removes trees, leading to a massive decrease in the biomass pool. With the loss of forest canopy protecting the ground, heavy tropical rainfall directly washes away the topsoil (accelerated soil erosion) and leaches nutrients deep down, while the lack of leaf litter input prevents replenishment. Consequently, the soil nutrient pool also decreases drastically.

Marking scheme

Award 1 mark for the correct answer B. No marks are given for incorrect answers.
Question 4 · MC
1 marks
Which of the following flowcharts correctly represents the positive feedback loop of melting Arctic sea ice?
  1. A.Rise in global temperature -> Melting of Arctic sea ice -> Decrease in planetary albedo -> Increase in absorption of solar radiation -> Rise in global temperature
  2. B.Rise in global temperature -> Melting of Arctic sea ice -> Increase in planetary albedo -> Increase in reflection of solar radiation -> Fall in global temperature
  3. C.Rise in global temperature -> Increase in evaporation -> Increase in low cloud cover -> Increase in reflection of solar radiation -> Fall in global temperature
  4. D.Rise in global temperature -> Thawing of permafrost -> Absorption of methane by soil -> Decrease in greenhouse effect -> Fall in global temperature

Answer

A

Worked solution

A positive feedback loop is a self-reinforcing process. Option A correctly traces this: rising global temperatures melt Arctic sea ice, replacing reflective ice with dark ocean water. This decreases the planetary albedo (reflectivity), causing the Earth's surface to absorb more solar radiation, which further elevates the global temperature, reinforcing the loop. Option B describes a negative feedback (and contains incorrect physical links). Option C is a cloud-radiation feedback which acts as a negative feedback. Option D incorrectly states that soil absorbs methane when permafrost thaws (permafrost thawing actually releases methane, increasing the greenhouse effect).

Marking scheme

Award 1 mark for the correct answer A. No marks are given for incorrect answers.
Question 5 · MC
1 marks
A group of students wants to investigate the "urban heat island effect" in a commercial district. Which of the following data collection methods can minimize the influence of extraneous variables?
(1) Measuring air temperature at different sites at the same time of day.
(2) Placing the digital thermometer under direct sunlight at all sites.
(3) Taking temperature readings at a standard height of 1.5 meters above ground.
(4) Selecting sites with identical wind directions and speeds.
  1. A.(1) and (2) only
  2. B.(1) and (3) only
  3. C.(2) and (4) only
  4. D.(3) and (4) only

Answer

B

Worked solution

Statement (1) is correct because air temperature varies throughout the day; simultaneous measurement controls the temporal variable. Statement (3) is correct because a standard height of 1.5m avoids ground conduction and controls the vertical gradient variable. Statement (2) is incorrect because direct sunlight heats the thermometer sensor directly, causing inaccurate air temperature readings (they should be shaded). Statement (4) is incorrect because wind patterns are highly altered by local buildings and topography, making it practically impossible to select sites with identical wind conditions; furthermore, wind is an inherent part of the microclimate being studied.

Marking scheme

Award 1 mark for the correct answer B. No marks are given for incorrect answers.
Question 6 · MC
1 marks
Which of the following reasons explain why the Shougang Group relocated its production plant from Beijing to Caofeidian (Hebei Province) in the 2000s?
(1) To reduce air pollution in the capital city before the Olympic Games.
(2) To utilize the deep-water port at Caofeidian for importing iron ore.
(3) To be closer to the market in Western China.
(4) To exploit the rich local iron ore deposits in Caofeidian.
  1. A.(1) and (2) only
  2. B.(1) and (4) only
  3. C.(2) and (3) only
  4. D.(3) and (4) only

Answer

A

Worked solution

Statements (1) and (2) are correct. Shougang's relocation was heavily driven by the government's mandate to improve Beijing's air quality prior to the 2008 Olympics. Caofeidian, as a deep-water port, allowed Shougang to transition from a resource-based location to a coastal location, facilitating the import of high-grade raw materials (iron ore and coal) via cheap maritime transport. Statement (3) is incorrect because Caofeidian is located on the coast of Northern China, far from Western China. Statement (4) is incorrect because Caofeidian itself does not possess rich mineral deposits; the plant relies on imported materials.

Marking scheme

Award 1 mark for the correct answer A. No marks are given for incorrect answers.
Question 7 · MC
1 marks
Which of the following is a human-induced root cause of chronic food shortage in the Sahel region?
  1. A.High variability of annual rainfall leading to frequent droughts
  2. B.Rapid population growth exceeding the carrying capacity of agricultural land
  3. C.Severe locust infestations destroying staple crops
  4. D.Low water-holding capacity of sandy soils

Answer

B

Worked solution

The question specifies a "human-induced root cause". Option B (rapid population growth) is a major human factor that leads to overcultivation and overgrazing, exceeding the carrying capacity of the marginal land and triggering desertification. Options A, C, and D are physical/natural factors (climatic variability, biological hazards, and soil characteristics respectively).

Marking scheme

Award 1 mark for the correct answer B. No marks are given for incorrect answers.
Question 8 · MC
1 marks
Which of the following physical conditions in Hong Kong make its hillslopes highly susceptible to mass wasting?
(1) Deeply weathered granitic rocks
(2) High density of vegetation cover
(3) Intense rainfall during summer monsoons
(4) Gentle slope gradients in suburban areas
  1. A.(1) and (3) only
  2. B.(1) and (4) only
  3. C.(2) and (3) only
  4. D.(2) and (4) only

Answer

A

Worked solution

Statements (1) and (3) are correct. Granite in Hong Kong is highly susceptible to deep chemical weathering under the hot and wet climate, leaving a thick layer of loose regolith. Intense summer rainfall increases pore water pressure and weight of this regolith, triggering landslides. Statement (2) is incorrect because vegetation roots bind soil and reduce infiltration, stabilizing slopes. Statement (4) is incorrect because gentle slopes decrease shear stress and lower the risk of mass wasting compared to steep slopes.

Marking scheme

Award 1 mark for the correct answer A. No marks are given for incorrect answers.
Question 9 · MC
1 marks
Which of the following sets of atmospheric and oceanic conditions is essential for the formation of a typhoon in the western North Pacific?
  1. A.Sea surface temperature above \(26.5^\circ\text{C}\), weak vertical wind shear, high Coriolis force
  2. B.Sea surface temperature below \(20^\circ\text{C}\), strong vertical wind shear, high Coriolis force
  3. C.Sea surface temperature above \(26.5^\circ\text{C}\), strong vertical wind shear, zero Coriolis force at the equator
  4. D.Sea surface temperature below \(20^\circ\text{C}\), weak vertical wind shear, zero Coriolis force at the equator

Answer

A

Worked solution

For a tropical cyclone (typhoon) to form, three key conditions must be met: (1) Sea surface temperatures must be above \(26.5^\circ\text{C}\) to provide ample heat and moisture. (2) Vertical wind shear must be weak so the warm air column can rise vertically without being disrupted. (3) High Coriolis force (occurring at least \(5^\circ\) latitude away from the equator) is needed to rotate the converging air. Therefore, Option A is correct.

Marking scheme

Award 1 mark for the correct answer A. No marks are given for incorrect answers.
Question 10 · MC
1 marks
Which of the following factors has driven the industrial restructuring of the Zhujiang Delta (PRD) region from "labor-intensive" to "high-tech" industries since the 2000s?
(1) Increasing land prices and labor wages in the PRD
(2) The implementation of the "Double Transfer" policy by the Guangdong government
(3) The discovery of rich local mineral resources in the PRD
(4) The appreciation of the Renminbi making export of cheap goods less competitive
  1. A.(1), (2) and (3) only
  2. B.(1), (2) and (4) only
  3. C.(1), (3) and (4) only
  4. D.(2), (3) and (4) only

Answer

B

Worked solution

Statements (1), (2), and (4) are correct. Rising land and labor costs in the PRD reduced the profit margins of labor-intensive industries. The Guangdong government's "Double Transfer" policy actively pushed labor-intensive factories out of the PRD to peripheral region and pulled high-tech, modern service industries into the PRD. The appreciation of the Renminbi also made cheap export goods less competitive, forcing industrial upgrading. Statement (3) is incorrect because the PRD has always been poor in mineral resources; its growth was never driven by local minerals.

Marking scheme

Award 1 mark for the correct answer B. No marks are given for incorrect answers.
Question 11 · MC
1 marks
Which of the following statements about constructive waves are correct?
1. The swash is stronger than the backwash.
2. They have a high wave frequency of over 15 waves per minute.
3. They are associated with the formation of depositional coastal landforms.
  1. A.1 and 2 only
  2. B.1 and 3 only
  3. C.2 and 3 only
  4. D.1, 2 and 3

Answer

B

Worked solution

Statement 1 is correct because constructive waves have a stronger swash which carries and deposits sediment onto the beach, and a weaker backwash. Statement 2 is incorrect because constructive waves have a low wave frequency (usually 6 to 9 waves per minute), whereas destructive waves have a high frequency. Statement 3 is correct as the dominant swash leads to net deposition, building up beaches and other depositional landforms. Therefore, the correct option is B.

Marking scheme

Award 1 mark for selecting the correct option B. No marks are given for other options.
Question 12 · MC
1 marks
Which of the following is a key environmental benefit of 'rehabilitation' compared to 'redevelopment' in the urban renewal of Hong Kong?
  1. A.Preserving existing building structures to reduce construction and demolition waste
  2. B.Increasing the residential plot ratio to maximize housing supply
  3. C.Widening narrow roads to improve local air ventilation
  4. D.Providing large-scale underground car parks to relieve roadside parking pressure

Answer

A

Worked solution

Rehabilitation involves repairing and restoring existing buildings rather than demolishing them. This significantly reduces the volume of construction and demolition waste disposed of in landfills, conserving resources and reducing environmental impacts compared to complete redevelopment. Options B, C, and D are typically outcomes of redevelopment.

Marking scheme

Award 1 mark for selecting the correct option A. No marks are given for other options.
Question 13 · MC
1 marks
Despite the massive biomass in tropical rainforests, the soil nutrient pool is relatively small. Which of the following are the reasons for this phenomenon?
1. Rapid nutrient uptake by dense and abundant vegetation.
2. Intense leaching of soil nutrients caused by heavy rainfall.
3. A very slow rate of organic decomposition on the forest floor.
  1. A.1 and 2 only
  2. B.1 and 3 only
  3. C.2 and 3 only
  4. D.1, 2 and 3

Answer

A

Worked solution

Statement 1 is correct because the dense tropical rainforest vegetation rapidly absorbs nutrients from the soil to support growth. Statement 2 is correct because the heavy and frequent rainfall in equatorial regions causes rapid leaching of soluble nutrients down through the soil profile. Statement 3 is incorrect because high temperatures and humidity in the rainforest promote extremely rapid decomposition of organic matter, not slow decomposition. Therefore, the correct option is A.

Marking scheme

Award 1 mark for selecting the correct option A. No marks are given for other options.
Question 14 · MC
1 marks
Arrange the following processes in the correct sequence to show how the positive ice-albedo feedback loop accelerates global warming:
1. Decrease in surface albedo
2. Rise in global temperature
3. Melting of glaciers and sea ice
4. Increase in absorption of solar radiation
  1. A.2 -> 1 -> 3 -> 4
  2. B.2 -> 3 -> 1 -> 4
  3. C.3 -> 2 -> 4 -> 1
  4. D.3 -> 4 -> 1 -> 2

Answer

B

Worked solution

The ice-albedo feedback is a positive feedback loop. It begins with a rise in global temperature (2), which causes the melting of glaciers and sea ice (3). As highly reflective ice is replaced by darker land or ocean surfaces, there is a decrease in surface albedo (1). This leads to an increase in the absorption of solar radiation (4), which further warms the planet, reinforcing the initial temperature rise. Thus, the correct sequence is 2 -> 3 -> 1 -> 4.

Marking scheme

Award 1 mark for selecting the correct option B. No marks are given for other options.
Question 15 · MC
1 marks
A student group planned a fieldwork study to investigate how traffic noise levels vary with distance away from a busy main road in Mong Kok. Which sampling method is the most appropriate for selecting the measurement locations?
  1. A.Random sampling
  2. B.Systematic sampling
  3. C.Stratified sampling
  4. D.Opportunistic sampling

Answer

B

Worked solution

Since the objective is to study the change in noise level *with distance* from a specific source (the main road), measurements should be taken at regular, predefined distance intervals (e.g., every 10 meters along a transect line perpendicular to the road). This is a classic application of systematic sampling. Random sampling may miss key intervals, while stratified sampling is used when dividing a population into sub-groups.

Marking scheme

Award 1 mark for selecting the correct option B. No marks are given for other options.
Question 16 · MC
1 marks
Which of the following factors best explains why major iron and steel plants in China have increasingly relocated to coastal areas since the late 20th century?
1. To utilize local iron ore resources along the coast.
2. To facilitate the import of high-grade raw materials by sea.
3. To access large domestic and international consumer markets.
  1. A.1 and 2 only
  2. B.1 and 3 only
  3. C.2 and 3 only
  4. D.1, 2 and 3

Answer

C

Worked solution

Statement 1 is incorrect because China's coastal areas generally lack abundant iron ore resources; coastal plants rely heavily on imports. Statement 2 is correct because coastal locations allow giant bulk carriers to dock, facilitating the cheap import of high-grade iron ore from countries like Australia and Brazil. Statement 3 is correct because major coastal cities and economic zones (like the Yangtze River Delta and Pearl River Delta) are the largest markets for steel consumption and allow easy export. Hence, 2 and 3 are correct.

Marking scheme

Award 1 mark for selecting the correct option C. No marks are given for other options.
Question 17 · MC
1 marks
In the Sahel region of Africa, which of the following are human-induced factors that aggravate soil degradation and lead to severe food shortages?
1. Overgrazing due to growing livestock populations.
2. High variability of annual rainfall.
3. Excessive cultivation of marginal land for cash crops.
  1. A.1 and 2 only
  2. B.1 and 3 only
  3. C.2 and 3 only
  4. D.1, 2 and 3

Answer

B

Worked solution

Statement 1 is a human factor: overgrazing destroys vegetation cover and compacts soil, leading to soil degradation. Statement 2 is incorrect because high variability of rainfall is a physical/natural factor, not human-induced. Statement 3 is a human factor: farmers over-cultivate fragile marginal lands to grow cash crops for income, depleting soil nutrients and accelerating desertification. Thus, 1 and 3 only are human-induced factors.

Marking scheme

Award 1 mark for selecting the correct option B. No marks are given for other options.
Question 18 · MC
1 marks
How does heavy and prolonged rainfall trigger a landslide on a soil slope in Hong Kong?
1. It increases the weight (surcharge) of the soil.
2. It increases pore water pressure, reducing the shear strength of the soil.
3. It causes rapid chemical weathering, immediately reducing the cohesion of the soil.
  1. A.1 and 2 only
  2. B.1 and 3 only
  3. C.2 and 3 only
  4. D.1, 2 and 3

Answer

A

Worked solution

Statement 1 is correct because rain water fills soil pores, increasing soil weight and thus gravitational pull downslope. Statement 2 is correct because high pore water pressure pushes soil particles apart, reducing friction and shear strength. Statement 3 is incorrect because chemical weathering is a long-term geological process and does not occur instantly to trigger a landslide during a single rainfall event. Therefore, the correct option is A.

Marking scheme

Award 1 mark for selecting the correct option A. No marks are given for other options.
Question 19 · MC
1 marks
Which of the following physical conditions are necessary for the formation of a tropical cyclone?
1. Sea surface temperature of at least \(26.5^\circ\text{C}\).
2. Location at least \(5^\circ\) latitude away from the Equator.
3. Strong vertical wind shear throughout the troposphere.
  1. A.1 and 2 only
  2. B.1 and 3 only
  3. C.2 and 3 only
  4. D.1, 2 and 3

Answer

A

Worked solution

Statement 1 is correct as high sea surface temperatures (at least \(26.5^\circ\text{C}\)) provide the necessary latent heat energy. Statement 2 is correct because a significant Coriolis force (which is near zero at the Equator and becomes sufficient beyond \(5^\circ\) latitude) is needed to induce the rotational movement of the cyclone. Statement 3 is incorrect because *weak* (not strong) vertical wind shear is required so that the vertical convective structure of the developing cyclone is not torn apart. Therefore, the answer is A.

Marking scheme

Award 1 mark for selecting the correct option A. No marks are given for other options.
Question 20 · MC
1 marks
Which of the following are the main factors driving industrial restructuring and upgrading in the Zhujiang (Pearl River) Delta since the 2000s?
1. Escalating labor and land costs.
2. Implementation of stricter environmental protection regulations.
3. Exhaustion of local coal and iron resources in the region.
  1. A.1 and 2 only
  2. B.1 and 3 only
  3. C.2 and 3 only
  4. D.1, 2 and 3

Answer

A

Worked solution

Statement 1 is correct as rapid economic growth led to shortages of cheap labor and land, forcing low-value-added, labor-intensive industries to relocate or upgrade. Statement 2 is correct as local governments implemented policies like 'Emptying the Cage for New Birds' and stricter environmental controls to phase out highly polluting industries. Statement 3 is incorrect because the Zhujiang Delta's early industrialization was never based on local coal and iron resource extraction; it was an export-oriented light manufacturing region. Therefore, the answer is A.

Marking scheme

Award 1 mark for selecting the correct option A. No marks are given for other options.

Section B

Attempt any TWO questions from this section (including the optional fieldwork question). Each carries 18 marks.
2 Question · 36 marks
Question 1 · Structured
18 marks
Sandy Bay is a micro-tidal coastal region experiencing a steady northward longshore drift. In 2015, a large offshore breakwater and a deep-water port were constructed to support regional trade. Table 1 shows the shoreline change rates (meters/year) at four monitoring stations (A, B, C, and D) along Sandy Bay before and after the construction of the breakwater. A positive value (+) indicates accretion (deposition), while a negative value (-) indicates erosion.

Table 1:
Station | Position relative to Breakwater | Shoreline Change Rate before 2015 (m/yr) | Shoreline Change Rate after 2015 (m/yr)
A | Updrift (North) | +0.5 | +2.1
B | Just behind Breakwater | +0.2 | +4.5
C | Downdrift (South, near-port) | -0.1 | -3.8
D | Far Downdrift (South) | -0.2 | -1.2

(a) (i) Describe the changes in the shoreline change rate at Sandy Bay after the construction of the breakwater in 2015. (3 marks)
(a) (ii) Explain the physical processes leading to the high accretion rate at Station B and the severe erosion at Station C. (5 marks)
(b) Apart from shoreline retreat, explain how the disruption of sediment transport might affect the coastal ecosystem of Sandy Bay. (4 marks)
(c) "Beach nourishment is a more sustainable alternative than constructing seawalls to mitigate erosion at Station C." Discuss this statement with reference to economic and environmental sustainability. (6 marks)

Answer

(a)(i) After 2015, accretion rate increased significantly at updrift stations A and B (e.g. B rose from +0.2 to +4.5 m/yr), while erosion rate accelerated at downdrift stations C and D (e.g. C shifted from -0.1 to -3.8 m/yr). (a)(ii) Station B is in the wave shadow zone behind the breakwater where wave energy is reduced, leading to deposition (salient/tombolo formation). The breakwater blocks longshore drift, causing "sediment starvation" at Station C (downdrift), where wave erosion continues without replenishment. (b) Disrupted sediment transport can smother benthic organisms at Station B due to rapid deposition, while severe erosion at Station C destroys sandy beach habitats, coastal vegetation, and turtle nesting grounds. (c) Beach nourishment is environmentally superior as it maintains natural beach dynamics and aesthetic value without wave reflection, but is economically demanding due to high recurring maintenance costs. Seawalls have high initial costs but are long-lasting, though they accelerate downdrift erosion.

Worked solution

(a) (i)
- Overall accretion rates increased in updrift stations (A, B) while erosion rates intensified in downdrift stations (C, D) after 2015. [1 mark]
- At Station B (just behind the breakwater), accretion rate spiked dramatically from \(+0.2\) m/yr to \(+4.5\) m/yr. [1 mark]
- At Station C, shoreline change shifted from mild erosion (\(-0.1\) m/yr) to severe erosion (\(-3.8\) m/yr). [1 mark]

(a) (ii)
- Longshore drift moves sediment from North to South along Sandy Bay. [1 mark]
- Station B is sheltered by the offshore breakwater, creating a wave shadow zone. Wave energy is greatly reduced due to wave refraction/diffraction. [1 mark]
- The reduced energy causes the waves to deposit their sediment load behind the breakwater, forming a salient or tombolo (high accretion). [1 mark]
- The breakwater acts as a physical barrier, blocking the sediment from being transported further south (downdrift). [1 mark]
- Consequently, Station C suffers from "sediment starvation". Waves continue to erode the coast at Station C, but there is no incoming sediment to replenish the lost sand, leading to severe erosion. [1 mark]

(b)
- At Station B, rapid sediment accumulation may smother benthic organisms, destroy seagrass beds, and reduce shallow water habitat diversity. [2 marks]
- At Station C, severe erosion destroys sandy beach habitats and turtle nesting sites. [1 mark]
- Loss of beach width leads to the destruction of coastal vegetation (e.g., coastal shrubs or mangroves), disrupting the local food web. [1 mark]

(c)
- Environmental sustainability:
- Beach nourishment (soft engineering) preserves the natural look of the beach, maintains sandy habitats, and does not cause wave reflection. [1 mark]
- Seawalls (hard engineering) destroy the natural shoreline habitat, disrupt coastal ecosystems, and cause wave reflection which accelerates erosion at adjacent downdrift coasts. [1 mark]
- Economic sustainability:
- Seawalls have high initial capital costs but low maintenance costs, providing long-term structural protection. [1 mark]
- Beach nourishment has lower initial construction costs but extremely high recurring costs, as nourished sand will continue to be washed away by waves and requires regular replenishment. [1 mark]
- Synthesis/Conclusion:
- Nourishment is environmentally more sustainable but financially challenging for local governments. A combination of soft engineering and minor hard structures may be optimal. [2 marks]

Marking scheme

Part (a)(i): Max 3 marks. Award 1 mark for overall trend, 1 mark for specific accretion station data, 1 mark for specific erosion station data.
Part (a)(ii): Max 5 marks. Award 1 mark for identifying the direction of longshore drift, 2 marks for explanation of Station B (wave shadow, energy reduction, deposition), 2 marks for Station C (barrier effect, sediment starvation, erosion without replenishment).
Part (b): Max 4 marks. Award 1 mark per valid ecological impact described. Max 2 marks for Station B impacts and max 2 marks for Station C impacts.
Part (c): Max 6 marks. Award up to 2 marks for environmental comparison, up to 2 marks for economic comparison, and up to 2 marks for a well-reasoned evaluative conclusion.
Question 2 · Structured
18 marks
Table 2 shows the soil ecological indicators under three different land-use types in a tropical rainforest region in Southeast Asia.

Table 2:
Land-use Type | Soil Organic Matter (%) | Litter Biomass (t/ha) | Soil Erosion Rate (t/ha/yr)
Primary Rainforest | 4.8 | 12.5 | 0.2
Shifting Cultivation (2-year fallow) | 2.1 | 3.2 | 15.4
Oil Palm Monoculture | 1.5 | 1.1 | 28.0

(a) Compare the soil organic matter, litter biomass, and soil erosion rates among the three land-use types shown in Table 2. (4 marks)
(b) With reference to the Gersmehl diagram of a tropical rainforest, explain why shifting cultivation and oil palm monoculture lead to a significant decline in soil organic matter and litter biomass. (6 marks)
(c) Explain how oil palm monoculture disrupts the nutrient cycle and energy flow of the tropical rainforest ecosystem. (4 marks)
(d) Evaluate whether agroforestry is a sustainable solution to balance economic development and ecological conservation in tropical rainforest regions. (4 marks)

Answer

(a) Soil organic matter and litter biomass are highest in Primary Rainforest (4.8% and 12.5 t/ha) and lowest in Oil Palm Monoculture (1.5% and 1.1 t/ha), while shifting cultivation is intermediate. Conversely, erosion rates increase exponentially from Primary Rainforest (0.2 t/ha/yr) to Oil Palm Monoculture (28.0 t/ha/yr). (b) Clearing forest drastically reduces the biomass store. Lower biomass reduces litter input (declining from 12.5 to 1.1-3.2 t/ha). In shifting cultivation, crop harvesting removes nutrients; short fallow prevents forest recovery. In oil palm monoculture, species simplified canopy reduces litter, while heavy rain leaches nutrients from the exposed soil. (c) Nutrient cycle: harvesting permanent removes nutrients, breaking the closed loop and forcing reliance on chemical fertilizers. Energy flow: simple monoculture lacks vertical layers, reducing primary productivity and niches, simplifying the food web and reducing energy transfer efficiency. (d) Agroforestry is highly sustainable as multi-layered canopy protects soil and increases litter input, while diversifying local incomes. However, it may yield lower short-term profits than commercial oil palm monoculture.

Worked solution

(a)
- Primary rainforest has the highest soil organic matter (\(4.8\%\)) and litter biomass (\(12.5\) t/ha), but the lowest soil erosion rate (\(0.2\) t/ha/yr). [1 mark]
- Oil palm monoculture has the lowest soil organic matter (\(1.5\%\)) and litter biomass (\(1.1\) t/ha), but the highest soil erosion rate (\(28.0\) t/ha/yr). [1 mark]
- Shifting cultivation values lie between the two (organic matter: \(2.1\%\); litter: \(3.2\) t/ha; erosion: \(15.4\) t/ha/yr). [1 mark]
- Comparison trend: As land-use intensity increases (from pristine to monoculture), soil organic matter and litter biomass decrease dramatically, while soil erosion rate increases exponentially. [1 mark]

(b)
- In the natural Gersmehl diagram of a rainforest, Biomass is the largest store, which constantly replenishes the Litter store. High temperatures/humidity cause rapid decomposition of litter, transferring nutrients to the Soil store. [1 mark]
- Under shifting cultivation:
- Biomass is slashed and burned, reducing the primary biomass store. [1 mark]
- Crop cultivation extracts nutrients directly from the soil. A short fallow period (only 2 years) is insufficient for secondary forest biomass to regenerate and replenish the litter layer. [1 mark]
- Under oil palm monoculture:
- Dense rainforest canopy is replaced by a single tree species with lower canopy density, greatly reducing the litter input (to \(1.1\) t/ha). [1 mark]
- Soil is exposed to intense rainfall, causing rapid leaching of nutrients from the soil store. [1 mark]
- Rapid water runoff accelerates soil erosion (\(28.0\) t/ha/yr), carrying away topsoil containing organic matter. [1 mark]

(c)
- Disruption of Nutrient Cycle:
- The natural closed, rapid nutrient cycle is broken. Continuous harvesting of oil palm fruits permanently removes nutrients from the ecosystem, rather than returning them via decomposition. [1 mark]
- The system relies heavily on chemical fertilizers, leading to soil acidification and water pollution (eutrophication). [1 mark]
- Disruption of Energy Flow:
- Simplification of the ecosystem (monoculture) reduces the vertical stratification (canopy layers), decreasing total primary productivity. [1 mark]
- Fewer ecological niches lead to a massive drop in biodiversity (loss of herbivores, carnivores, and decomposers), which simplifies the food web and reduces energy transfer efficiency. [1 mark]

(d)
- Economic benefits:
- Provides diverse income sources for farmers (crops + timber/fruit trees), reducing vulnerability to market price fluctuations of a single crop. [1 mark]
- Ecological benefits:
- Restores a multi-layered canopy which reduces rainfall impact, lowering soil erosion and maintaining soil organic matter through high litter input. [1 mark]
- Limitations:
- Yields of commercial cash crops (like oil palm) may be lower than in intensive monoculture plantations, reducing short-term corporate profits. [1 mark]
- Conclusion / Evaluation:
- Agroforestry is a highly sustainable compromise, but requires government subsidies and technical training to encourage commercial planters to adopt it. [1 mark]

Marking scheme

Part (a): Max 4 marks. Award 1 mark for describing Primary Rainforest data, 1 mark for Oil Palm data, 1 mark for Shifting Cultivation data, and 1 mark for summarizing the general comparative trend across the three land types.
Part (b): Max 6 marks. Award 1 mark for explaining the baseline Gersmehl cycle in pristine forest; 2 marks for shifting cultivation (clearing, crop uptake, short fallow); 3 marks for oil palm (reduced litter input, high leaching, severe soil erosion carrying organic matter).
Part (c): Max 4 marks. Award 2 marks for explaining the nutrient cycle disruption (harvesting removal, chemical fertilizers) and 2 marks for energy flow disruption (reduced canopy/stratification, loss of trophic levels, simplified food webs).
Part (d): Max 4 marks. Award up to 2 marks for arguments supporting agroforestry (economic/ecological sustainability), 1 mark for limitations, and 1 mark for a balanced conclusion.

Section C

Attempt any ONE question from this section. Each carries 12 marks.
1 Question · 12 marks
Question 1 · Short Essay
12 marks
Explain how the expansion of commercial agriculture leads to the degradation of tropical rainforest ecosystems. Discuss whether international market-based mechanisms (such as eco-labeling and REDD+) are effective in conserving these rainforests.

Answer

Refer to the marking scheme and solution for detailed explanatory and evaluative points.

Worked solution

### Part 1: How commercial agriculture degrades the rainforest ecosystem (Max 6 marks)
- **Disruption of the Nutrient Cycle:** Commercial agriculture often involves large-scale 'slash-and-burn' clearing. Burning vegetation releases stored nutrients instantly into the soil, but these are rapidly depleted or washed away by heavy rainfall (leaching) because there is no dense forest canopy to protect the soil. Since the continuous supply of organic litter (leaf fall) is cut off, the nutrient cycle is broken, leading to soil infertility.
- **Loss of Biodiversity and Habitat Fragmentation:** Monoculture farming (e.g., vast plantations of oil palm or soy) replaces highly diverse multi-layered forests with a single species. This destroys habitats, disrupts food webs, and causes severe species extinction. Forest fragmentation isolates wildlife populations, making them vulnerable to local extinction.
- **Alteration of the Hydrological Cycle:** Removing forest cover reduces evapotranspiration. This decreases atmospheric humidity and local convectional rainfall, resulting in a drier local climate. Without forest roots to bind the soil and a canopy to intercept rain, soil erosion and surface runoff increase, leading to siltation in local rivers.
- **Microclimate Changes:** The loss of shade increases ground-level solar radiation and soil temperatures, accelerating the decomposition of organic matter and drying out the soil, which increases the vulnerability of the remaining forest to wildfires.

### Part 2: Evaluation of market-based mechanisms (Max 6 marks)
- **Arguments for their effectiveness:**
- **Economic Incentives (REDD+):** REDD+ assigns a monetary value to carbon stored in forests, offering financial compensation to developing nations for preserving forests. This creates a direct financial alternative to agricultural conversion.
- **Shifting Consumer Demand (Eco-labeling):** Certification schemes (e.g., FSC for timber, RSPO for palm oil) allow consumers to identify sustainably sourced products. This pressures multi-national corporations (MNCs) to adopt sustainable practices to maintain market access.
- **Promotion of Sustainable Management:** These schemes encourage agroforestry and selective logging, balancing economic development with ecological conservation.
- **Limitations and Challenges:**
- **The Leakage Problem:** Protecting a specific forest area under a REDD+ project may simply shift logging and agricultural expansion to unprotected adjacent areas or other countries.
- **High Verification Costs and Corruption:** Monitoring, reporting, and verifying (MRV) carbon stocks require high technology and administrative costs. Poor governance and corruption in developing countries may lead to greenwashing.
- **Indigenous Rights and Land Tenure:** REDD+ programs sometimes lead to state centralization of forest land, marginalizing indigenous communities who have sustainably managed the forests for generations.
- **Incomplete Market Coverage:** Eco-labeled products often carry a price premium, limiting their demand in price-sensitive developing markets, while non-certified cheap agricultural products still find buyers globally.

Marking scheme

### Marking Scheme (Total: 12 marks)

**Detailed Marking Rubric:**

- **Explain how commercial agriculture degrades the ecosystem (Max 6 marks):**
- *Award 1-2 marks* for simple descriptions pointing out that farming clears trees and causes loss of plants and animals.
- *Award 3-4 marks* for explaining the connection between agricultural activities (clearing, monoculture) and ecosystem processes (nutrient loss, soil erosion, food web disruption).
- *Award 5-6 marks* for systematic, comprehensive explanations using appropriate geographical terminology (e.g., nutrient cycle disruption, leaching, evapotranspiration decrease, habitat fragmentation, microclimate changes).

- **Discuss the effectiveness of market-based mechanisms (Max 6 marks):**
- *Award 1-2 marks* for brief descriptions of what eco-labels or REDD+ are, with minimal evaluation.
- *Award 3-4 marks* for structured arguments showing both sides (benefits like economic incentives/consumer demand shift, and limitations like cost/leakage), but lacking in-depth analysis or specific examples.
- *Award 5-6 marks* for a well-balanced, critical, and comprehensive evaluation of both eco-labeling and REDD+. Candidate demonstrates clear understanding of the complexity (e.g., addressing issues of leakage, verification costs, indigenous land rights, and global market unevenness). Guidelines are well-supported by geographical concepts.

Section D

Attempt any ONE question from this section. Each carries 18 marks.
1 Question · 18 marks
Question 1 · Structured
18 marks
Sandy Bay is a coastal area known for its scenic sandy beach and a prominent spit extending across the mouth of an adjacent estuary.

(a) Describe and explain the formation of the spit at Sandy Bay. (5 marks)

(b) A deepwater port with a long breakwater has recently been constructed updrift of Sandy Bay. Explain how this construction might disrupt the coastal processes and affect the beach and the spit. (7 marks)

(c) To mitigate the coastal erosion, the local government is considering beach nourishment instead of constructing seawalls. Discuss the effectiveness of using beach nourishment (soft engineering) over seawalls (hard engineering) in protecting Sandy Bay. (6 marks)

Answer

Refer to the solution and marking scheme for detailed responses to parts (a), (b), and (c).

Worked solution

### Part (a)
The spit is a depositional feature formed primarily by longshore drift (LSD). Prevailing winds blow at an angle to the shoreline, causing waves (swash) to carry sediment up the beach obliquely. Backwash pulls the sediment straight down the beach under the influence of gravity. This zig-zag movement transports sediment along the coast. When the coastline changes direction at the estuary mouth, the wave energy decreases, leading to the deposition of sand and shingle. Over time, continuous deposition extends the beach material outward into the open water, forming a spit.

### Part (b)
The construction of a long breakwater updrift traps sediment carried by longshore drift on its updrift side. This starves Sandy Bay (located downdrift) of its natural sediment supply. Since the incoming sand supply is cut off while waves continue to transport existing sediment away, the rate of erosion at Sandy Bay beach exceeds the rate of deposition. Consequently, the beach shrinks and the spit begins to erode and may eventually breach or disappear due to the lack of sediment replenishment.

### Part (c)
Beach nourishment (soft engineering) is highly effective for Sandy Bay because it preserves the natural beauty and recreational value of the beach, supporting tourism. It does not introduce harsh concrete structures that disrupt ecosystems. However, it is only a temporary solution as waves and longshore drift will continue to erode the added sand, requiring expensive, recurring maintenance.
Seawalls (hard engineering) provide immediate and durable protection against wave attack. However, they are visually intrusive and destroy the natural landscape. Furthermore, they cause wave reflection which accelerates the erosion of the sandy beach in front of the wall, eventually destroying the beach entirely.
Therefore, beach nourishment is more sustainable and appropriate for a recreational area like Sandy Bay despite its high long-term maintenance costs.

Marking scheme

### Part (a) (Max 5 marks)
* Longshore drift (LSD) as the primary process. [1 mark]
* Explanation of oblique swash due to prevailing wind direction. [1 mark]
* Explanation of vertical backwash due to gravity. [1 mark]
* Zig-zag transport of sediment along the coast. [1 mark]
* Change in coastline direction at the estuary reduces wave energy, leading to deposition. [1 mark]
* Continuous deposition extends beach material into the open water to form a spit. [1 mark]

### Part (b) (Max 7 marks)
* Breakwater acts as a barrier to longshore drift. [1 mark]
* Traps sediment on the updrift side, causing accumulation there. [1 mark]
* Creates "sediment starvation" / sand deficit on the downdrift side (Sandy Bay). [1 mark]
* Rate of coastal erosion exceeds the rate of deposition. [1 mark]
* Serious beach erosion occurs, leading to a reduction in beach width/area. [1 mark]
* Spit loses its sediment supply, leading to erosion and potential breaching. [1 mark]
* Destructive wave action dominates over constructive action due to loss of sediment buffer. [1 mark]

### Part (c) (Max 6 marks)
* **Beach nourishment (soft engineering)**:
* *Pros*: Maintains beach aesthetics, sustains tourism, environmentally friendly. [1 mark]
* *Cons*: Temporary fix, requires continuous and high-cost replenishment. [1 mark]
* **Seawalls (hard engineering)**:
* *Pros*: Immediate, robust, long-lasting barrier against strong waves. [1 mark]
* *Cons*: Ruins natural landscape (negative for tourism), triggers wave reflection which destroys the beach. [1 mark]
* **Evaluation/Conclusion**: Justified preference for beach nourishment for recreational sites like Sandy Bay. [1 mark]

Section E

Attempt any ONE question from this section. Each carries 12 marks.
1 Question · 12 marks
Question 1 · Short Essay
12 marks
Explain how geological factors and wave action interact to form erosional coastal landforms. Discuss the effectiveness of hard engineering measures in protecting these coastal areas from erosion.

Answer

N/A

Worked solution

Interaction of waves and geology: Wave erosion processes such as hydraulic action and abrasion target weaknesses in coastal rocks. Hydraulic action compresses air in rock cracks, widening them, while abrasion uses wave-transported sediments to wear down rock faces. Geological factors, including rock type, joints, faults, and fold structures, determine the rate and pattern of erosion. On discordant coasts, alternating bands of hard and soft rock erode at different rates, forming headlands and bays. Along headlands, wave refraction concentrates wave energy, accelerating erosion along joints and faults to form sea caves, arches, stacks, and stumps. On cliffs, wave-cut notches are eroded at the base, leading to cliff collapse and the formation of wave-cut platforms. Effectiveness of hard engineering: Hard engineering measures, such as seawalls, groynes, and breakwaters, offer immediate and strong physical barriers. Seawalls reflect wave energy, protecting coastal infrastructure. Breakwaters reduce wave energy offshore, protecting harbors. However, their long-term effectiveness is limited. Seawalls can cause beach scouring as reflected waves erode the beach profile. Groynes trap sediment updrift but cause severe erosion downdrift due to beach starvation (terminal groyne effect). Furthermore, they are highly expensive to construct and maintain, visually obtrusive, and can damage marine ecosystems. Thus, while highly effective in the short term for high-value areas, they often create secondary environmental and erosional issues downstream.

Marking scheme

Explanation of physical processes and geology (max 6 marks): - Wave erosion processes (hydraulic action, abrasion/corrosion) explained (2 marks). - Geological factors (rock resistance, jointing/faulting, coastal alignment) explained (2 marks). - Sequential formation of landforms (e.g., crack to cave to arch to stack, or cliff notch to wave-cut platform) (2 marks). Discussion of hard engineering (max 6 marks): - Identification of hard engineering measures (e.g., seawalls, groynes, breakwaters) (1 mark). - Arguments for effectiveness (immediate protection, high durability, protects high-value property) (2 marks). - Arguments against/limitations (high cost, beach scouring, downdrift erosion/terminal groyne effect, ecological damage) (3 marks).